1. Field of the Invention
The present invention relates to an optical scanner for reading indicia such as bar code symbols and a field of view reader for reading indicia such as bar code symbols. In particular the invention relates to such systems when including dual light sources.
2. Discussion of the Prior Art
Known optical systems for reading an indicia such as bar code symbols comprise a light source, a focusing system for directing a light beam from the light source onto the bar code symbol and a detector for receiving light reflected from the bar code symbol and generating a representative electrical signal. In some cases it is desired to provide a reader capable of reading bar code symbols presented in more than one operating range and accordingly it has been suggested that a first and second light source be provided having different operating ranges. For example, a reader has been suggested comprising a first and second laser diode light source having different operating ranges determined, for example, by respective lens systems. The laser diodes are off-set from one another and a mirror is introduced in order to combine beams from the two lasers. Such a system is known as a dynamic focusing system.
U.S. Pat. No. 4,085,423 discloses an information reproducing apparatus including optical information recording media such as video disks including two laser sources generating light of different wavelengths and a dichroic filter reflecting light of one wavelength and transmitting light of the other wavelength in order that the respective light beams can be used for different purposes.